Extant in Kaliyuga´s 36th century ( 5 th century A.D.), Arya Bhatta has been a great teacher of astronomy in Bharat whose work on astronomy, known as Aryabhatiyam, is regarded as the oldest book of its kind, that; the later astronomers and astrologers acknowledge as the Arya Principle (Arya Siddhanta). Far earlier than Copernicus, Arya Bhatta propounded and adopted the theory that not Sun but Earth revolves around the former.